Extrusion head for extruding a tubular parison for producing liquid containers and related nozzle group

Abstract

The present invention relates to an extrusion head (1) for extruding thermoplastic material within a blow-molding system for blow molding containers (10), characterized in that it comprises a slotted opening (6) for the passage of a group (20) of nozzles (8). The invention also relates to a dispensing group (20) for such extrusion head (1) comprising a support (15), an extension (7), and / or two or more nozzles (8) fixed to the support (15) by means of the extension (7).

Description

[0001] EXTRUSION HEAD FOR EXTRUDING A TUBULAR PARISON FOR

[0002] PRODUCING LIQUID CONTAINERS AND RELATED NOZZLE GROUP

[0003] The present invention falls within the field of methods for producing liquid- filled containers in parison form, wherein, in a stage defined as the “blowing” stage (BLOW), the plastic is extruded in a tubular form which, through a pressure difference exerted on its wall, adheres to the walls of a mold to form the container. In the subsequent “sealing” stage (SEAL), the container is closed by sealing specific sections of the container, and, before performing the final seal, which closes the opening through which the container can be filled, a filling stage (FILL) may be provided, wherein the container can also be filled with a liquid via a movable nozzle.

[0004] In particular, the invention concerns an extrusion head for producing a tube for carrying out the aforementioned method, which comprises at least one internal flow channel for supplying a fluid thermoplastic plastic, formed so as to present a ring-shaped extrusion opening, corresponding to the desired cross-section of the tube.

[0005] Extrusion heads of this type are described in patents EP0361123 and WO201 9057499, which depict an extrusion head based on the same principle, i.e. extruding material in a tubular form, which presents multiple holes inside, each allowing a respective nozzle and sterile air to pass through.

[0006] A particular requirement of these extrusion heads is to distribute the plastic material uniformly along the entire surface of the tubular form, so as to guarantee the correct thickness and the correct exit speed of the tubular from the extrusion head.

[0007] Such solutions are not optimal from several points of view.

[0008] For example, in machines where such extrusion heads are mounted, it is usually possible - as well as necessary - to replace the molds, for example to modify the dimensions of the container to be molded. This change of molds may involve the need to modify the interaxial distances between the nozzles. In the case of the extrusion heads in the above documents, this is impossible unless part or all of the extrusion head is changed.

[0009] Furthermore, in known systems the nozzles are surrounded by the extrusion head, which prevents heat dispersion, increasing their temperature. This makes it necessary to add a cooling jacket around the individual nozzles, but this would increase the cost and complexity.

[0010] Moreover, the sterile airflow is divided around each nozzle and may not be uniform.

[0011] A further drawback is the very size of the holes: if plastic material sticks to a nozzle, when the latter rises, this material would be pushed into these holes, with the risk of total or partial blockage, and making it very difficult to remove later.

[0012] Another drawback is that the nozzles, having to pass through rather narrow holes, must be supported by individual equally narrow supports in order to pass through the holes themselves, resulting in a series of rather long and narrow tools, that are complex to make, assemble, and remove for maintenance.

[0013] Instead, a commonly existing problem in the BFS process or just in the blowforming process is that when the parison is formed from the mold, a part of the parison (usually the sides) is discarded because it is not properly formed.

[0014] This is necessary to properly form the central vials, however, a lot of material is wasted, which, in the case of medical products, must be of a very pure and therefore expensive grade.

[0015] The plastic material that comes into contact with the solution must, in fact, be pure, to reduce interactions with the pharmaceutical product.

[0016] In the extrusion of vials with an interaxial distance of 8 mm, the traditional design of a cylindrical parison would be inefficient. In fact, for example, to accommodate 10 nozzles on a width of 80 mm, a parison with a diameter of at least 120 mm would be necessary, equivalent to a semicircumference of approximately 188 mm. However, only 80 mm of this length would actually be used to produce the vials, while the remaining 108 mm would constitute a waste, equal to 57% of the material.

[0017] The solution proposed by the present invention provides a parison with a slotted shape, which allows for a significant reduction in material waste. Specifically, by designing a slot with the two foci that are 80 mm apart, and a width of 40 mm, a semiperimeter of approximately 140 mm is obtained. This results in a waste reduced to only 40 mm, or 28%. This waste reduction becomes even more significant as the number of nozzles and the interaxial distance of the vials increase, thereby improving the production efficiency.

[0018] In the context of the above-mentioned requirements, the main aim of the invention is therefore to propose an extrusion head for extruding thermoplastic plastic to produce containers, which overcomes the drawbacks of the prior art.

[0019] In particular, an aim of the invention is to produce an extrusion head that makes it possible to create containers with interaxial distances that can vary depending on the request.

[0020] The aim of the invention is, therefore, to create a parison with a greater length and a smaller width, maintaining the form as rectilinear as possible in the areas where it is necessary to precisely control the thickness of the extruded material. To this purpose, the design of a slot that is useful for extruding a parison with an elongated form is considered.

[0021] Another aim of the invention is to facilitate the cooling of the nozzles, for example by allowing an improvement in the cooling capacity of the nozzles.

[0022] Furthermore, an aim of the invention is to make the system for producing containers in thermoplastic plastic more versatile, resulting in significant savings in terms of space and warehouse management.

[0023] These and other aims, that will become more apparent below, are achieved by a container produced using an extrusion head for a system for forming containers, as will be more evident hereafter in this description.

[0024] An object of the invention is a first plate of an extrusion head for extruding thermoplastic material within a blow-molding system for blow molding containers, characterized in that it comprises a slotted opening with a minor axis for the passage of a dispensing group equipped with at least two dispensing holes for dispensing liquid into such containers during the forming process.

[0025] Preferably, the first plate can have multiple slotted openings, each traversed by one or more dispensing groups equipped with at least two dispensing holes. This allows the blow-molding system to be highly versatile and adaptable to any container mold, even when replacing molds having containers with differing interaxial distances.

[0026] A further object of the invention is a second plate of an extrusion head for extruding thermoplastic material within a blow-molding system for blow molding containers, characterized in that it comprises a distribution channel equipped with a first section adjacent to the material inlet channel and equipped with a projection on the vertical sectional plane passing through the minor axis of the slot, a second section for material outlet equipped with a first extension, and a third section located between the first section and the second section equipped with a second extension, inclined to increase the thickness of the internal part of the extrusion head and enhance the uniformity of the tubular form to be extruded, wherein each section has a horizontal component and a vertical component on the vertical sectional plane passing through the minor axis of the slot.

[0027] In detail, the overall measurement of the vertical component of the first section, second section, and third section is less than or equal to the minor axis of the slot multiplied by a first coefficient of 2.47.

[0028] This advantageously allows an extrusion head to be obtained with distribution channels having a vertical component that is reduced compared to those in the prior art and allowing a uniform distribution of the thermoplastic material along the edge of the slot, preventing deformations and breakages of the tubular parison.

[0029] Furthermore, the overall measurement of the horizontal component of the first section, second section, and third section, and of the distance between the second section and the edge of the slotted opening can be less than or equal to the minor axis of the slot multiplied by a second coefficient of 4.87.

[0030] In this case, the distribution channel can be inserted within an extrusion head that is extremely compact and versatile and at the same time robust and reliable over time.

[0031] In particular, the first extension of the second section is less than the minor axis of the slot multiplied by a third coefficient equal to 1.2 and / or the second extension of the third section is less than the minor axis of the slot multiplied by a fourth coefficient of 1 .8.

[0032] Furthermore, according to the invention, the distance between the edge of the slot and the beginning of the second section and / or the projection can be less than the minor axis of the slot multiplied by the fourth coefficient of 1 .8.

[0033] According to the invention, the inclination of the third section can be between 25° and 65°, preferably 45°.

[0034] Moreover, according to the invention, the distribution channel can have an elongated cross-section in its second segment, so as to form a parison tube with an elongated cross-section. In this way, it is advantageously possible to save space and reduce plastic waste.

[0035] In this case, the distribution channel can consist of two halves that mirror each other relative to a vertical plane, for example to the main development plane of the second segment, which advantageously allow a better distribution of the material during the creation of the parison tube.

[0036] Furthermore, according to the invention, the distribution channel can have different areas, each fed by a respective distinct inlet channel, so as to allow the formation of containers equipped with zones having different properties and characteristics.

[0037] In particular, it is possible to provide a first area intended for creating a first wall of the containers, and a second area intended for creating a second wall of the containers. In this way it is possible to produce containers with a more rigid wall and a completely collapsible one, to allow the complete ejection of the contained liquid.

[0038] Another possibility, either in addition to or as an alternative to the previous one, is to provide a third area intended for creating the container sealing edges intended to be discarded. This advantageously allows the use of a third material, for example a non-pure or recycled one, for the parts intended to be discarded, such as those outermost to the matrix of the containers.

[0039] Furthermore, an object of the invention is also an extrusion head comprising such first and second plates, or an extrusion head where the first and second plates are the same plate.

[0040] A further object of the invention is a dispensing group for the extrusion head, comprising a support, an extension, and / or two or more dispensing nozzles connected to the support. The support advantageously allows multiple nozzles to be moved together, while the extension allows for the use of shorter nozzles, which are therefore easier to manufacture, replace, and transport, or it allows dispensing holes to be used directly in place of the nozzles.

[0041] According to the invention, the support can be made with internal cooling channels.

[0042] Further features and advantages of the invention will become more apparent from the description of a preferred, but not exclusive, embodiment of the extrusion head, according to the invention, illustrated for indicative and non-limiting purposes with the aid of the accompanying drawings, wherein:

[0043] - Figure 1 shows a top view of the extrusion head of the invention, in a first variant with a single material inlet channel;

[0044] - Figure 2 shows a sectional view of the extrusion head of Figure 1 , with the dispensing group inserted;

[0045] - Figure 3 shows a top view of the extrusion head of the invention, in a second variant with a double material inlet channel;

[0046] - Figure 4 shows a top view of the distribution channels of the extrusion head of the invention, in a third variant with a double material input channel;

[0047] - Figure 5 shows a front view of the parison tube and the containers produced therefrom, not yet detached;

[0048] - Figure 6 shows a perspective view of the parison tube of Figure 5, with welding lines as obtained using the variant of Figure 4;

[0049] - Figure 7a shows the dispensing group with respective support and extension of the invention;

[0050] - Figure 7b shows the dispensing group with respective support, extension and nozzles of the invention;

[0051] - Figure 8 shows a top view of the parison tube of Figure 5;

[0052] - Figure 9 shows a top view of the parison tube of Figure 5, with areas as obtained using the variant of Figure 3;

[0053] - Figure 10 shows a schematic representation of various embodiments of the slot through which the nozzle group of the invention passes;

[0054] - Figure 11 shows a detail of Figure 2;

[0055] - Figure 12 shows a simulation of the parison tube at the pressure (about 300 BAR) obtainable through a first prior patent with individual holes for the respective nozzle;

[0056] - Figure 13 shows an example of simulation of the parison tube of Figure 12, wherein the individual holes have been replaced with a slot, with a lower pressure (10 BAR);

[0057] - Figure 14 shows a simulation of the parison tube at the pressure (about 300 BAR) obtainable through a second prior patent with individual holes for the respective nozzle;

[0058] - Figure 15 shows an example of simulation of the parison tube of Figure 14, wherein the individual holes have been replaced with a slot, with a lower pressure (10 BAR).

[0059] Figure 1 shows a top view of the extrusion head of the invention, generically indicated by 1 , equipped with a slotted opening 6, for the passage of a group 20 of nozzles 8, fixed to a support 15, so as to fill a band of containers 10 formed within a mold to be positioned below the extrusion head 1 .

[0060] In the following, reference will be made to the embodiment shown in the figures, which provides a single slot 6 traversed by a single support 15 to which all the nozzles 8 are fixed, but it is natural that in preferred variants of the invention multiple slots are provided in the same extrusion head, each traversed by a single support with multiple nozzles fixed thereto, or multiple supports are provided that traverse a single slot.

[0061] In this way, advantageously, it is not necessary, as in the prior art, to have very long individual nozzles, but the single support 15, which supports at least one group 20 of nozzles 8 via an extension 7, allows these nozzles 8 to be shorter, and therefore easier to replace and manufacture, as shown in Figure 7b.

[0062] Figure 7a shows a particular variant of the invention wherein an extension 7, directly equipped with dispensing holes 8a and without requiring actual nozzles, is fixed to the support 15.

[0063] In a preferred variant of the invention, the extensions 7 and / or the nozzles 8 may be covered with a coating or layer of insulating material, or they may be made of an insulating material, for example PTFE or PEEK, to reduce heat dispersion and, consequently, the need for cooling inside them.

[0064] Furthermore, if it becomes necessary to change the arrangement of the nozzles 8 to adapt it to a new shape and size of containers 10 to be formed, it is sufficient to replace the support 15, without having to change the entire extrusion head 1 .

[0065] This support 15, the extensions 7 and / or the nozzles 8 can be made with internal cooling channels, to also facilitate their production by 3D printing.

[0066] Such cooling, in particular, can be carried out using:

[0067] - channels for cooling liquid

[0068] - heat pipes

[0069] - vacuum chambers

[0070] - Peltier modules or

[0071] - combinations of these techniques.

[0072] Thanks to the single opening 6 for multiple nozzles, the airflow is therefore more uniform.

[0073] Finally, cleaning such extrusion head 1 of any pieces of plastic material that have remained stuck is easier because the spaces are larger.

[0074] Each of the halves 31 and 32 of the distribution channel is connected to the extruder via a respective supply channel 34 for supplying the parison mass. It is possible to adjust the flow in the channels 34 independently of each other, using flow adjustment screws (not shown).

[0075] The distribution channel 31 , 32 leads to the slotted opening 6.

[0076] In its lower segment 5, adjacent to the slotted opening 6, the distribution channel also presents the shape of a slot, which extends without interruptions in the circumferential direction of the slotted opening 6 itself.

[0077] An issue that arises from creating this slotted opening 6 is the weakening of the internal part of the structure of the extrusion head 1 .

[0078] The solution proposed by the present invention is to make the distribution channel inclined in its cross-section 4, possibly only in the terminal part of the distribution channel, for example at an angle between 25° and 65° - for example, at 45°, so as to increase the thickness of the section of the extrusion head 1 , located between the slotted opening 6 and the distribution channel, reinforcing the internal part of the head as much as possible and also reducing the loads, that would otherwise tend to deform the internal part of the structure.

[0079] In this way, in fact, this section is advantageously prevented from undergoing high deformations, due to the high pressures of the extrusion process, which would impact the uniformity of the tubular form.

[0080] An issue that arises when the distribution channels are inclined is that in the curved parts the internal surface of the distribution channels varies greatly.

[0081] To better explain this concept, we can take as an example a truncated cone, with a 45° inclination: the surface of the upper face of the truncated cone is much smaller than the lower surface. This effect is similar within the conical distribution channels.

[0082] This effect does not occur in the linear parts, and this could lead to instability and a non-uniform distribution of the plastic material in the final flat tube exiting the extrusion head.

[0083] The distribution channels must always be smaller / narrower towards the exit direction of the plastic in order to compress it and make it uniform.

[0084] This reduction in section must result in a consistent extrusion surface at each height along the oval of the parison to prevent some parts from exiting faster than others and thereby avoid a completely crooked parison.

[0085] To solve this problem, the shape of the extrusion head 1 has been designed to ensure that the reduction of the internal surface of the distribution channels remains uniform in both the flat and curved segments.

[0086] In particular, at the end 3 facing the distribution channels 34, each of the halves 31 and 32 of the distribution channel 30 has a linear development parallel to the long sides of the slotted opening 6, without touching each other.

[0087] At the lower end of the extrusion head 1 , however, the halves 31 and 32 join together, forming a development that runs completely parallel to the slotted opening 6.

[0088] The inclination of the two halves 31 and 32 of the distribution channel causes their upper ends to be farther from the slotted opening 6 than their lower ends, so that the opening of the flat parison tube 9 is as close as possible to the slotted opening 6.

[0089] In this way, the material poured into the channel 30 follows a path inclined relative to a vertical axis and converging towards the centre of the extrusion head 1.

[0090] Advantageously, as shown in Figure 3, it is possible to feed the two halves 31 and 32, with two distinct materials that have different properties, for example, in the first half 31 there could be a very flexible material entering from the material input channel 2, and in the second half 32 there could be a more rigid and / or thicker material, arriving from the second material inlet channel 11.

[0091] In this way, it is advantageously possible to create the two opposite sides of a vial with two different types of material, the first of which can completely collapse onto the second to eject all the liquid contained within it.

[0092] Moreover, advantageously, as shown in Figure 4, the two halves 31 and 32 can be further subdivided to create the parison tube 9 with a further type of material along its curved part 13.

[0093] In detail, with reference to Figure 6, this latter solution allows the parison flat tube 9 to be produced from two different types of material: a pure material coming from the first inlet channel 2 (Fig. 4), used to create the two parallel segments 12 of the flat tube, which will then generate the body of the vials 10, while another material entering from the second inlet channel 11 (Fig. 4) - which could even consist of waste from the process itself - is used to create the curved parts 13, which will then be discarded (see Figure 5), with welding lines 14 between the two materials in correspondence with the outermost weld of the outermost vial, resulting in an obvious economic advantage. Finally, a further innovation (not shown in the figures) would be to design this head to extrude multilayer film. This extrusion head would consist of two linear multilayer extruders, joined at the sides by two segments of an additional plastic material, creating a single closed tubular form with 2 multilayer segments.

[0094] To create a parison tube with an elongated cross-section, so as to save space and avoid excessive plastic waste, the extrusion head 1 has an elongated shape, and presents a distribution channel, consisting of two halves 31 and 32 that mirror each other relative to the plane connecting the two half -shells of the mold.

[0095] The flat parison tube 9, exiting the final segment 5 of the distribution channel, is formed in the mold matrix, which has groups of containers 10 positioned adjacent to each other.

[0096] To allow the simultaneous filling of all the containers 10 formed by the mold matrix, there are filling nozzles 8 that are guided in longitudinal movement within the slotted opening 6 by one or more supports 15.

[0097] In order to create a compact system, these supports 15 extend through the extrusion head 1 along the central separation plane between the two half-shells of the mold and the two halves 31 and 32 of the distribution channel.

[0098] The lower end of the slotted opening 6 is positioned centrally between the two halves 31 and 32 of the distribution channel, so that the free lower ends of the nozzles 8 are positioned exactly equidistant from the long sides of the flat parison tube 9 that surrounds them.

[0099] In Figure 2, the halves 31 and 32 of the distribution channel are shown in section, along with the respective inclined segments 4 and the terminal segments 5.

[0100] The nozzles 8, connected to the support 15 which is in turn equipped with an extension 7, pass through the inside of the slot 6 which is adapted to allow the nozzles 8 to pass through the slot and reach the inside of the containers.

[0101] With reference to Figure 10, the slot 6 can be schematically considered similar to an ellipse with a minor axis equal to 2A.

[0102] The distance B between the two foci of an ellipse with radius A must be greater than 8 mm. In the schematic representation, the segments of the perimeter between the two foci of the ellipse can be straight or curved. If they are curved, the difference C between the minor axis and the distance between a focus and the vertex of the closest ellipse (equal to the major axis - distance between the foci / 2) must not exceed 2 / 3 of B, otherwise the slotted shape would be lost.

[0103] Further referring to Figure 10, the extrusion head 1 is designed to produce a parison 9 with an elongated shape. This elongated shape is obtained thanks to the presence of an elongated slot 6 in the extrusion head 1 . The slot 6 has a greater length than an equivalent circular hole. In particular, the slot 6 can be considered similar to an ellipse, wherein for example the distance B between the two foci is 8 mm greater than the radius A of the equivalent circular hole. This configuration of the slot 6 allows a parison 9 to be obtained with an elongated shape, which can be used for producing plastic containers with less waste of material.

[0104] The extrusion head 1 is also designed to allow the passage of one or more dispensing groups 20 through the slot 6. Each dispensing group 20 may comprise two or more nozzles 8 or 8a, which may be positioned within the slot 6.

[0105] In particular, with reference to Figure 11 , the dimension D2, corresponding to the extension of the cross-section 4 of the distribution channel, is less than the minor axis D1 of the slot 6 multiplied by the coefficient 1.8, to optimize the overall dimensions of the extrusion head.

[0106] The dimension D3, corresponding to the distance between the edge of the slot 6 and the lower segment 5 of the distribution channel, is less than the minor axis of the slot 6 multiplied by the coefficient 1.8. This dimension D3 may be considered as less than 63 mm.

[0107] The dimension D4, corresponding to the extension of the lower segment 5 of the distribution channel, is less than the minor axis of the slot 6 multiplied by the coefficient 1.2. Overall, this dimension D4 is less than 42 mm.

[0108] The dimension D5, corresponding to the projection of the channel 32 on the vertical sectional plane passing through the slot 6 itself, is less than the minor axis of the slot 6 multiplied by the coefficient 1 .8. Overall, this dimension D5 is less than 63 mm. This configuration of the slot 6 is designed to nullify the deformation of the parison 9 at the intermediate point of the slot 6, thus solving one of the common problems associated with traditional extrusion systems.

[0109] In essence, a crucial measurement for the creation of this extrusion head that allows the slot configuration described above is the sum of the vertical component of D2 + D4. This measurement D7 corresponds to the vertical component of an entire distribution channel (the left one 31 , 4, 5, or the right one 32, 4, 5). D7, considering the cross-section 4 inclined by 45°, is less than the minor axis D1 of the slot 6 multiplied by the coefficient 2.47.

[0110] In addition, to still obtain a compact and at the same time sufficiently robust extrusion head, the sum of D3 + the horizontal component of D2 + D5 must remain below a certain threshold. This measurement D6 is equal to the overall distance between the end 33 of the feed channel 34 facing the distribution channel 30 and the edge of the slotted opening 6, and therefore it corresponds to the distance D3 added to the horizontal component of an entire half of the distribution channel 30 (the left one 31 , 4, 5, or the right one 32, 4, 5). D6, considering the cross-section 4 inclined by 45°, is less than the minor axis D1 of the slot 6 multiplied by the coefficient 4.87.

[0111] In the extrusion process, the molten plastic material is passed through the extrusion head 1. In particular, the specific dimensions of the extrusion head 1 , as described above, contribute to form a parison 9 with an elongated shape and to reduce the deformation of the parison 9 at the intermediate point of the slot 6.

[0112] However, unlike the present invention, the known extrusion heads do not allow the creation of a slot suitable for nullifying the deformation of the parison at the intermediate point of the slot itself.

[0113] Referring to Fig. 12, a simulation of the parison extruded according to the extrusion head described in the prior art patent no. EP 0 361 123 A2 was carried out: at a normal operating pressure (from 50 to 400 BAR, in this case 300 BAR) in the internal part of the head, where the holes for the passage of the individual dispensers are made, the holes undergo a negligible deformation.

[0114] As can be seen in correspondence with the hole there is a slight deformation of a few hundredths.

[0115] Referring to Fig. 13, a simulation of an example of a version with a slot, further of the head of patent no. EP 0 361 123 A2, was carried out, wherein the individual holes were replaced with a slot.

[0116] The pressure was lowered to 10 BAR, and it can be seen that despite this very low pressure, that is insufficient for the effective operation of the machine, there is a strong deformation, of 10 mm, at the intermediate point of the slot. In other words, it is clear that the shape does not allow for the creation of a slot that solves the technical problem.

[0117] A scale on the right side of the image indicates the range of deformation values, from 0.00000 (less deformation) to 10.0534 (more deformation). This scale helps to quantify the degree of deformation in different areas of the component.

[0118] The simulation aims to demonstrate the limitations and challenges associated with this particular design in operating conditions.

[0119] Referring to Fig. 14, a simulation of the parison extruded according to the extrusion head described in the prior art patent no. WO2019\057499 was carried out: at the pressure (about 300 BAR) in the internal part of the head, where the holes for the passage of the individual dispensers are made, the holes undergo a negligible deformation.

[0120] Referring to Fig. 15, a simulation of an example of a version with a slot, further of the head of patent no. WO2019\057499, wherein the individual holes were replaced with a slot, at a pressure much lower than the operating pressure, was carried out.

[0121] At 10 BAR, the simulation shows a strong deformation of about 2.8 mm at the intermediate point of the slot, indicating that the shape of the extrusion head does not allow for the creation of a slot that solves the technical problem.

[0122] This suggests that the extrusion head in the prior art may present significant limitations when it comes to minimize the deformation of the parison during the extrusion process.

[0123] In particular, the significant deformation observed at the intermediate point of the slot may lead to a non-uniform distribution of the thickness of the parison walls, which in turn may affect the quality of the final container produced, as well as making it impossible for the nozzles to pass through.

[0124] All the details of the invention may be replaced by other technically equivalent elements. In practice, the materials used, as well as the specific shapes and dimensions, may be varied according to the contingent needs and the state of the art.

[0125] When the construction features and techniques mentioned in the following claims are accompanied by reference signs or numbers, these reference signs or numbers have been included with the sole purpose of enhancing the intelligibility of the claims themselves and, consequently, they do not in any way limit the interpretation of each element identified, purely by way of example, by such reference signs.

Claims

EXTRUSION HEAD FOR EXTRUDING A TUBULAR PARISON FORPRODUCING LIQUID CONTAINERS AND RELATED NOZZLE GROUPCLAIMS1. An extrusion head (1 ) for extruding a tubular form (9) of thermoplastic material within a blow-molding system for blow molding containers (10), comprising a slotted opening (6) with a minor axis (D1 ) for the passage of a dispensing group (20) equipped with at least two dispensing holes (8; 8a) for dispensing liquid into said containers (10) during the formation process, characterized in that it comprises a distribution channel (30) equipped with a first section (31 , 32) adjacent to the material inlet channel (2, 11 ) and equipped with a projection (D5) on the vertical sectional plane passing through the minor axis (D1 ) of the slot (6), a second section(5) for material outlet equipped with a first extension (D4), and a third section (4) located between the first section and the second section equipped with a second extension (D2), inclined to increase the thickness of the internal part of the extrusion head (1 ) and enhance the uniformity of the tubular form (9) to be extruded, each section (31 , 32, 5, 4) having a horizontal component and a vertical component on the vertical sectional plane passing through the minor axis (D1 ) of the slot (6), wherein the overall measurement (D7) of the vertical component of the first section (31 , 32), second section (5), and third section (4) is less than or equal to the minor axis (D1 ) of the slot (6) multiplied by a first coefficient of 2.47.

2. The extrusion head (1 ) as in claim 1 , characterized in that the overall measurement (D6) of the horizontal component of the first section (31 , 32), of the second section (5), and of the third section (4), and of the distance (D3) between the second section (5) and the edge of the slotted opening (6) is less than or equal to the minor axis (D1 ) of the slot (6) multiplied by a second coefficient of 4.87.

3. The extrusion head (1 ) as in claim 1 or 2, characterized in that the first extension (D4) of the second section (5) is less than the minor axis (D1 ) of the slot(6) multiplied by a third coefficient equal to 1 .2 and / or the second extension (D2) of the third section (4) is less than the minor axis (D1 ) of the slot (6) multiplied by a fourth coefficient of 1 .8.

4. The extrusion head (1 ) as one of claims 1 -3, characterized in that it has multiple slotted openings (6), each traversed by one or more of said dispensing groups (20).

5. The extrusion head (1 ) according to one of claims 1 -4, wherein the distance (D3) between the edge of the slot (6) and the beginning of the second section (5) and / or the projection (D5) is less than the minor axis (D1 ) of the slot (6) multiplied by the fourth coefficient 1 .8.

6. The extrusion head (1 ) according to one of claims 1 -5, wherein the inclination of the third section (4) is between 25° and 65°, preferably 45°.

7. The extrusion head (1 ) according to one of claims 1 -6, wherein the distribution channel (3) has in its second segment (5) an elongated cross-section so as to form the tubular form (9) of thermoplastic material with an elongated crosssection (12).

8. The extrusion head (1 ) according to claim 7, wherein the distribution channel (3) consists of two halves (31 , 32) that mirror each other relative to the main development plane of the second section (5).

9. The extrusion head (1 ) according to any of claims 1 -8, characterized in that the distribution channel (3) has areas (31 , 32, 13) fed by distinct inlet channels (2, 11 ), so as to allow the formation of containers (10) equipped with zones with different properties and / or characteristics.

10. The extrusion head (1 ) according to claim 9, wherein said areas (31 , 32, 13) fed by distinct inlet channels (2, 11 ) comprise a first area (31 ) intended for the creation of a first wall of the containers (10), and a second area (32) intended for the creation of a second wall of the containers (10).

11. The extrusion head according to claim 9 or 10, wherein said areas (31 , 32, 13) fed by distinct inlet channels (2, 11 ) comprise a first area (31 ) and a secondarea (32) intended for the creation of the front and rear walls of the containers (10), and a third area (13) intended for the creation of the sealing edges (13) of the containers (10) intended to be discarded.

12. A dispensing group (20) for the extrusion head (1 ) of one of claims 1 -11 , characterized in that it comprises a support (15), an extension (7), and / or two or more nozzles (8; 8a) connected to the support (15).

13. The dispensing group (20) according to claim 12, wherein at least one of the support (15) and the extension (7) is made with internal cooling channels.

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